A fuel cell includes an electrode for generating an electrochemical reaction with a fuel and an oxidizer, a polymer electrolyte membrane for transferring protons generated by the reaction, and a separator (also called a “separation plate”) for supporting the electrode and the polymer electrolyte membrane.
A polymer electrolyte fuel cell has been increasingly used as a fuel cell for vehicle. The polymer electrolyte fuel cell has high efficiency, high current density and output density, and a short starting time. Further, the polymer electrolyte fuel cell does not easily corrode, and does not need to control an electrolyte due to the use of a polymer electrolyte.
In the automotive industries, active research is being carried out on the polymer electrolyte fuel cell because it discharges only water as exhaust gas.
The polymer electrolyte fuel cell produces electrical energy while generating water and heat through an electrochemical reaction between a fuel including hydrogen, and an oxidizer such as air.
That is, in the polymer electrolyte fuel cell, the supplied fuel is separated into protons and electrons in the catalyst of the anode, and the separated protons are transferred to the cathode through a polymer electrolyte membrane. In this case, the separated protons are combined with a supplied oxidizer and electrons received through an external conductor, thereby generating the electrical energy while generating water.
In a typical fuel cell for a vehicle, in order to obtain high potential, unit cells are stacked according to required potential. The stacked unit cells are called a stack.
The electrode of the fuel cell includes a mixture of hydrogen ion carriers and a catalyst. In an initial operation of the fuel cell, activities of electrochemical reaction may be low since reactants are unable to reach the catalyst when the moving path of the reactants is clogged, the hydrogen ion carriers forming a triple phase interface are not easily hydrolyzed in the initial operation, and it is difficult to secure the continuous mobility of hydrogen ions and electrons.
Accordingly, in order to secure maximum performance of fuel cells after the fuel cells are assembled in a fuel cell stack, that is, an electrical generation aggregate of the fuel cells which includes a membrane electrode assembly (MEA) including an electrode, a polymer electrolyte membrane, and a separator, an activation and performance evaluation procedure needs to be performed on the fuel cells.
The activation and performance evaluation removes remaining impurities that flow in a process of manufacturing a membrane-electrode assembly and a fuel cell stack, activates sites that do not participate in a reaction, secures a moving passage in which reactants may move to a catalyst, and secures a hydrogen ion passage by sufficiently hydrolyzing an electrolyte included in the polymer electrolyte membrane and an electrode.
The activation of fuel cells is performed in various ways according to fuel cell manufacturers, but a major activation method is a long-time operation at a specific voltage.
After a plurality of fuel cells is stacked, a conventional system for activating the fuel cells supplies a fuel and an oxidizer to the fuel cells and activates the fuel cells by applying electrical energy, which is generated from the fuel cells, to an electronic load.
In this case, the activation and performance evaluation process of fuel cells is performed after the fuel cells are assembled into a fuel cell stack. If a failure occurs in a specific fuel cell that forms the fuel cell stack, the fuel cell stack may explode. Thus, the defective fuel cell must be replaced or removed, and the fuel cells must be assembled again. Accordingly, a time delay occurs in performing the activation and performance evaluation.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.